Preprints
https://doi.org/10.5194/tc-2020-99
https://doi.org/10.5194/tc-2020-99

  03 Jun 2020

03 Jun 2020

Review status: this discussion paper is a preprint. It has been under review for the journal The Cryosphere (TC). The manuscript was not accepted for further review after discussion.

Inter-and Intra-annual Surface Velocity Variations at the Southern Grounding Line of Amery Ice Shelf from 2014 to 2018

Zhaohui Chi and Andrew G. Klein Zhaohui Chi and Andrew G. Klein
  • Department of Geography, Texas A&M University, College Station, Texas, 77845-3147, USA

Abstract. The ice flow rate through the grounding line of the Amery Ice Shelf (AIS) is vital to understanding the mass discharge received from its three primary tributary glaciers. Previous studies have indicated a stable multiyear average surface velocity distribution in the convergence area of AIS. However, the surface velocity variations, especially short-term fluctuations, in the AIS have been relatively undocumented. This study investigated inter-annual and intra-annual surface velocity variations along the southern segment of AIS grounding line from 2014 to 2018. Using feature tracking to derive surface velocity for five consecutive austral summers and winters, it was found that AIS’s upstream end has experienced a steady ~ 5 % inter-annual increase in surface velocity. Surface velocity increases were observed in 2014/2015 (0.25 ± 0.02 m/d) and in 2017/2018 (0.21 ± 0.02 m/d) respectively. Surface velocities in winters were lower than the summers except for 2016, which had a 0.12 m/d surface velocity decrease from winter to summer. Although flowing slower than the other two glaciers, Fisher Glacier exhibited the highest inter-annual increase (8.56 ± 4.36 %) and the largest intra-annual variation (−5.41 ± 5.65 %) in surface velocity of the three studied glaciers. While the surface velocity observed in 2018 was generally close to the observed velocity in 1989, the magnitude of velocity variations observed during the 2014–2018 period is similar to the differences in velocities measured at the grounding line since 1989. This indicates continued relative stability in the surface velocities at the grounding line of these three tributary glaciers but also indicates that caution should be applied when interpreting long-term differences based on a limited number of measurements. This study demonstrated the capability of feature tracking to monitor the multidecadal changes of surface velocity.

Zhaohui Chi and Andrew G. Klein

 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Zhaohui Chi and Andrew G. Klein

Zhaohui Chi and Andrew G. Klein

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Short summary
This study examines surface velocity variations of temporal and spatial distribution along the southern segment of the grounding line of Amery Ice Shelf, East Antarctica. As the variations in surface velocities observed for three major tributary glaciers over the study period of 2014–2018 are similar in magnitude to the range of velocities to that of measured since 1989 of the AIS suggests caution needs to be applied when comparing limited measurements from various decades.